Radio Frequency IDentification (RFID) is utilized in many applications including smart cards, transport payments, product tracking and personnel tracking. In each of these applications, an RFID tag or transponder is attached to or incorporated within a product or person. Then, the RFID tag is used to identify the product or person using radio waves.
There are many different types of RFID tags. The three main types include passive, semi-passive and active tags. Passive tags require no power source whereas semi-passive tags use a small power source and active tags need an internal power source.
Passive RFID tags are capable of functioning without an internal power source. A tiny amount of energy is needed for the integrated circuit within the tag to function, and the electrical current induced in the antenna by the incoming radio frequency signal provides enough power. It is common for passive tags to use the antenna to collect power from the incoming signal and also to transmit the outbound signal. Furthermore, since passive tags have no internal power source, they are able to be produced extremely small. Passive tags also generally have a very long life span since there is no internal power source to drain or fail.
Semi-passive RFID tags utilize a small battery which powers the RFID tag thus removing the need for specialized two-way antennas which are used in passive RFID tags.
Active RFID tags require an internal power source which is used to power the integrated circuit to generate an outgoing signal. Active tags are considered to be more reliable than passive tags with their ability to transmit at higher power levels. Active tags are also able to be made relatively small, such as the size of a coin. As technology improves, active tags will eventually become even smaller.
As mentioned above, RFID has many applications. Another application includes being used within a driver's license. There has been significant discussion of utilizing RFID within drivers' licenses for the purposes of identifying drivers without having to manually inspect the license. Licenses would not have to be put into a reader device like they are today where a magnetic strip is used to store information. Rather, the license could be scanned using an RFID scanner. “Wired News: RFID Driver's Licenses Debated” http://www.wired.com/news/privacy/0,1848,65243,00.html?tw=wn_tophead—5 Although utilizing RFID within driver's licenses is known, the concept has only been implemented to remove the need for swiping the driver's license.
Furthermore, due to the fourth amendment of the Constitution which prohibits unauthorized searches and seizures, police officers are unable to pull over drivers for simply suspecting they are driving without a license. The police must first have a reason to pull over someone, such as a traffic violation. This presents a problem because there are many individuals who drive illegally without a valid license after it has been suspended, revoked or has never been received for one reason or another. Yet the police are generally unable to do much to stop such occurrences since their opportunities to cite these violators are limited. The unlicensed drivers are potentially hazardous and would be ticketed under state law for driving without a license if discovered. Hence, an implementation that does not violate the fourth amendment yet is able to detect drivers without a valid license is highly desirable.